The Asters are a huge genus of wildflowers native all across the northern hemisphere. From Europe and Asia, there are many fine species, selections and hybrids, but they tend to be spring and early summer bloomers. Here in North America, our native species and improved native selections of asters are late summer and fall bloomers. Thus they are an integral part of the food chain for native bees and honey bees as well as butterflies and migrating Monarchs. They also provide invaluable late season color in our gardens and landscapes.
However, much to my bewilderment, these outstanding native asters are mostly overlooked when gardeners shop for perennial flowers. Perhaps it's because they aren't in bloom in the spring when many folks do their flower shopping. But I can say with confidence that the late season asters are worth seeking out for their easy-to-grow nature, their beauty in flower and their essential role in habitat creation for pollinators.
These perennials that require very little effort on the part of gardeners. It's as easy as one, two, three.
Plant them in full sun.
Plant them in less-than-ideal soils. Average garden loam, clay, and sandy soils are all good. Avoid wet soil locations and stay away from overly rich, heavily composted soils.
Go easy on the water and fertilizer. Asters grow best with "tough love". Give them modestly amended soil (a handful of Yum Yum Mix and good quality compost at planting time) and regular watering to get them established the first growing season. Come the second growing season, back off and let them take care of themselves with a minimum of care.
Maintaining Established Asters
Leave them standing over the winter months and cut back the stems to just a couple of inches above the crown in mid-spring.
Fertilize in the fall. Don't use chemical fertilizers on Asters (or any other garden plants for that matter). Use Yum Yum Mix (or the equivalent) which is actually what I call a "soil food". Yum Yum Mix is a blend of nutrients that feed the soil microbes, beneficial soil fungi and earthworms necessary for a healthy living soil. The soil "digests" these nutrients leaving behind the nitrogen, phosphorus, potassium and trace elements that the plants need.
Go easy on the mulch. Many plant-derived mulch materials like coarse compost, composted leaves and composted bark enrich the soil over time as they break down. Thrifty growers like asters don't like or need rich soil, so these soil building mulches should not be used on Asters. Leave them un-mulched in moderate climates. In harsh, dry conditions, use pine needles or crushed gravel.
Companion Plants for Fall Blooming Asters
Bluebird Smooth Aster blooms from last summer through fall and beautifully compliments yellow rudbeckia with it's contrasting purple blooms.
There are other beautiful and pollinator-friendly perennials that can be planted with fall blooming asters that will accentuate their beauty, enhance your garden's diversity and improve the garden's ability to provide beneficial habitat.
Solidago (Goldenrod) - Goldenrod doesn't cause allergies (its pollen is not windborne, but must be moved by bees). There are a number of improved cultivars that are different from common roadside plants. And most of them are propagated from cuttings thus, won't reseed themselves and become weedy.
Schzachyrium scoparium (Little Bluestem Grass) - A native companion found growing with asters in their native habitat. Colorful fall foliage and seeds for seed-eating songbirds are two (among many) attributes that recommend this prairie grass.
Sporobolus heterolepis (Prairie Dropseed Grass) - Another native companion found growing with asters in their prairie habitat. In addition to providing brilliant yellow fall foliage, this grass is a four-season textural masterpiece in the garden.
Bluebird Smooth Aster (Aster laevis 'Bluebird') is one of the very best of our native Asters, providing a profusion of 1-inch violet-blue flowers held in clusters at the tips of the growing stems. Attractive blue-green foliage provides garden interest prior to the showy flowers. 'Bluebird' was introduced by Dr. Richard Lightly of the Mt. Cuba Center Botanical Gardens where it was rated as the #1 performing Aster in their garden evaluation of the genus.
Raydon's Favorite' Aster (Aster oblongifolius) is one of our most reliable native perennial asters. It has a strikingly beautiful mounded appearance with attractive foliage. Blooming in mid- to late fall, it displays large clusters of blue-purple, daisy-like flowers on a 2-3 ft. tall multi-stemmed plant.
Vigorous and unfussy in the garden, 'Raydon's Favorite' Aster grows in rocky, loam and clay soils and withstands difficult growing conditions very well. It was a top-rated selection in the Chicago Botanic Garden trials, exhibiting exceptional flower production and outstanding winter hardiness. In cultivation for many years, it can be considered an heirloom plant and was introduced into cultivation by San Antonio gardener Raydon Alexander, who got it in the wilds of Tennessee.
Purple Dome Aster (Aster novae-angliae 'Purple Dome')- This selection of New England aster is notable for its tidy, compact, mounding habit and luscious deep lavender-purple flowers. Sometimes affected by mildew in humid climates, it has been a star in the arid western US where the foliage stays "clean and green."
Lady In Black Aster (Aster lateriflorus 'Lady in Black')- Grow this native perennial Aster for its very attractive purplish-black foliage and clouds of small rose-red centered white daisies. Blooming in late summer and early fall, 'Lady in Black' is an easy-to-grow perennial that thrives in a variety of soil and climatic conditions. The plant received a top 5-star rating in the Chicago Botanic Gardens extensive six year evaluation of the asters.
First Snow Heath Aster (Aster ericoides 'First Snow') is a star of the fall garden, that blooms with a profusion of tiny white flowers held on husky, densely branched stems. The nectar-rich flowers are magnets for attracting all kinds of bees and butterflies including migrating Monarchs. This native aster selection is a sun-lover and easily grown in all types of soil including clay. First Snow Heath Aster is a must-have perennial for late season flowers.
'Purple Dome' is a New England type aster that blooms in early fall with hundreds of deep lavender-purple flowers. This dwarf plant has a neat mounding habit and is a perfect choice to edge pathways and fill small spaces.